Coupling of Magnetite Particles with Microwaves at Temperatures lower than the Curie Point

Research output: Contribution to journalConference article

Abstract

Effect of the particle size (d) and apparent density on the coupling of microwaves with Fe3O4 was investigated at temperatures lower than the Curie point, TC ≃ 585 °C. Two samples in the form of tablet with particle sizes of 45-75 μm (MT75) and <45 μm (MT45) and one sample in the form of powder with a particle size of <45 μm (MP45) were heated in multi-mode and maximum E- and H-field modes using a microwave generator at a frequency of 2.45 GHz. According to the results, an earlier temperature increase and also a higher temperature was achieved in the sample heated in the maximum H-filed mode. Regarding the incubation time in all samples, the particle size of Fe3O4 has no significant effect on the time required for the initial temperature increase in the presence of the H-field. In the maximum E-field mode, a shorter time was required for the temperature increase in the MT75 sample than MT45. At T≤Tc, magnetic loss and Joule loss are the dominant heating mechanisms in the presence and absence of the H-field, respectively. Magnetic loss is independent of the particle size whereas Joule loss which is influenced by electrical conductivity, affected by particle size. Therefore, above-mentioned effect of the particle size is attributed to the dominant heating mechanism. Also, some of the small particles seems to be transparent owing to a greater penetration depth (δ), ca. 80 μm at room temperature causing an earlier onset of temperature increase in sample with larger particle size, MT75. Moreover, microwave absorption in a sample with higher apparent density, MT45, was lower because of a higher electrical conductivity of sample in tablet form, MT45, than powder form, MP45.

Original languageEnglish
Article number012042
JournalIOP Conference Series: Materials Science and Engineering
Volume424
Issue number1
DOIs
Publication statusPublished - Oct 13 2018
Event9th International Symposium on Electromagnetic Processing of Materials, EPM 2018 - Awaji Island, Hyogo, Japan
Duration: Oct 14 2018Oct 18 2018

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Ferrosoferric Oxide
Magnetite
Particle size
Microwaves
Magnetic leakage
Temperature
Powders
Tablets
Heating

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Engineering(all)

Cite this

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title = "Coupling of Magnetite Particles with Microwaves at Temperatures lower than the Curie Point",
abstract = "Effect of the particle size (d) and apparent density on the coupling of microwaves with Fe3O4 was investigated at temperatures lower than the Curie point, TC ≃ 585 °C. Two samples in the form of tablet with particle sizes of 45-75 μm (MT75) and <45 μm (MT45) and one sample in the form of powder with a particle size of <45 μm (MP45) were heated in multi-mode and maximum E- and H-field modes using a microwave generator at a frequency of 2.45 GHz. According to the results, an earlier temperature increase and also a higher temperature was achieved in the sample heated in the maximum H-filed mode. Regarding the incubation time in all samples, the particle size of Fe3O4 has no significant effect on the time required for the initial temperature increase in the presence of the H-field. In the maximum E-field mode, a shorter time was required for the temperature increase in the MT75 sample than MT45. At T≤Tc, magnetic loss and Joule loss are the dominant heating mechanisms in the presence and absence of the H-field, respectively. Magnetic loss is independent of the particle size whereas Joule loss which is influenced by electrical conductivity, affected by particle size. Therefore, above-mentioned effect of the particle size is attributed to the dominant heating mechanism. Also, some of the small particles seems to be transparent owing to a greater penetration depth (δ), ca. 80 μm at room temperature causing an earlier onset of temperature increase in sample with larger particle size, MT75. Moreover, microwave absorption in a sample with higher apparent density, MT45, was lower because of a higher electrical conductivity of sample in tablet form, MT45, than powder form, MP45.",
author = "A. Amini and Ko-Ichiro Ohno and Takayuki Maeda and Kazuya Kunitomo",
year = "2018",
month = "10",
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doi = "10.1088/1757-899X/424/1/012042",
language = "English",
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journal = "IOP Conference Series: Materials Science and Engineering",
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T1 - Coupling of Magnetite Particles with Microwaves at Temperatures lower than the Curie Point

AU - Amini, A.

AU - Ohno, Ko-Ichiro

AU - Maeda, Takayuki

AU - Kunitomo, Kazuya

PY - 2018/10/13

Y1 - 2018/10/13

N2 - Effect of the particle size (d) and apparent density on the coupling of microwaves with Fe3O4 was investigated at temperatures lower than the Curie point, TC ≃ 585 °C. Two samples in the form of tablet with particle sizes of 45-75 μm (MT75) and <45 μm (MT45) and one sample in the form of powder with a particle size of <45 μm (MP45) were heated in multi-mode and maximum E- and H-field modes using a microwave generator at a frequency of 2.45 GHz. According to the results, an earlier temperature increase and also a higher temperature was achieved in the sample heated in the maximum H-filed mode. Regarding the incubation time in all samples, the particle size of Fe3O4 has no significant effect on the time required for the initial temperature increase in the presence of the H-field. In the maximum E-field mode, a shorter time was required for the temperature increase in the MT75 sample than MT45. At T≤Tc, magnetic loss and Joule loss are the dominant heating mechanisms in the presence and absence of the H-field, respectively. Magnetic loss is independent of the particle size whereas Joule loss which is influenced by electrical conductivity, affected by particle size. Therefore, above-mentioned effect of the particle size is attributed to the dominant heating mechanism. Also, some of the small particles seems to be transparent owing to a greater penetration depth (δ), ca. 80 μm at room temperature causing an earlier onset of temperature increase in sample with larger particle size, MT75. Moreover, microwave absorption in a sample with higher apparent density, MT45, was lower because of a higher electrical conductivity of sample in tablet form, MT45, than powder form, MP45.

AB - Effect of the particle size (d) and apparent density on the coupling of microwaves with Fe3O4 was investigated at temperatures lower than the Curie point, TC ≃ 585 °C. Two samples in the form of tablet with particle sizes of 45-75 μm (MT75) and <45 μm (MT45) and one sample in the form of powder with a particle size of <45 μm (MP45) were heated in multi-mode and maximum E- and H-field modes using a microwave generator at a frequency of 2.45 GHz. According to the results, an earlier temperature increase and also a higher temperature was achieved in the sample heated in the maximum H-filed mode. Regarding the incubation time in all samples, the particle size of Fe3O4 has no significant effect on the time required for the initial temperature increase in the presence of the H-field. In the maximum E-field mode, a shorter time was required for the temperature increase in the MT75 sample than MT45. At T≤Tc, magnetic loss and Joule loss are the dominant heating mechanisms in the presence and absence of the H-field, respectively. Magnetic loss is independent of the particle size whereas Joule loss which is influenced by electrical conductivity, affected by particle size. Therefore, above-mentioned effect of the particle size is attributed to the dominant heating mechanism. Also, some of the small particles seems to be transparent owing to a greater penetration depth (δ), ca. 80 μm at room temperature causing an earlier onset of temperature increase in sample with larger particle size, MT75. Moreover, microwave absorption in a sample with higher apparent density, MT45, was lower because of a higher electrical conductivity of sample in tablet form, MT45, than powder form, MP45.

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